1. Field of the Invention
This invention relates to the connection of double walled insulated vent pipes or tubes, particularly, although not exclusively, flexible vent tubing.
2. Review of the Art
Particularly with the development of higher efficiency heating appliances, and in some other applications, there is a requirement for double walled insulated flue or vent pipes. Where prefabricated double walled rigid pipes are utilized, an installation must be assembled from available pipe lengths and connectors, which requires detailed advance planning, as well as layout compromises in many installations. For this reason the use of flexible double walled tubing, which can be bent to some degree and cut to length to suit a particular installation, is attractive. Unfortunately, it is not easy to form satisfactory connections between lengths of such tubing. Each wall of the tubing is typically of very thin metal which may be little more than 0.1 millimeters thick, and provides a wholly unsatisfactory anchorage for the metal screws or rivets commonly utilized for securing pipe in conventional couplings.